﻿#include "string.h"

namespace A {
	const  size_t string::npos = -1;

	void string::reserve(size_t n) {
		if (n > _capacity) {
			//多开一个给\0
			char* tmp = new char[n + 1];
			strcpy(tmp, _str);
			delete[] _str;
			_str = tmp;
			_capacity = n;
		}
	}
	void string::push_back(char ch) {
		if (_size == _capacity) {
			reserve(_capacity == 0 ? 4 : _capacity * 2);
		}
			_str[_size] = ch;
			++_size;
			_str[_size] = '\0';
		
	}
	void string::append(const char* str) {
		size_t len = strlen(str);
		if (_size + len > _capacity) {
			reserve(_size + len > 2 * _capacity ? _size + len : 2 * _capacity);
		}
		strcpy(_str + _size, str);
		_size += len;
	}

	string& string::operator+=(char ch) {
		push_back(ch);
		return *this;
	}

	string& string::operator+=(const char* str)
	{
		append(str);
		return *this;
	}
	void string::insert(size_t pos, char ch) {
		assert(pos <= _size);
		if (_size == _capacity) {
			reserve(_capacity == 0 ? 4 : _capacity * 2);
		}
		size_t end = _size + 1;
		while (end > pos) {
			_str[end] = _str[end - 1];
			end--;
		}
		_str[pos] = ch;
		++_size;
	}
	void string::insert(size_t pos, const char* str) {
		size_t len = strlen(str);
		if (_size + len > _capacity) {
			reserve(_size + len > 2 * _capacity ? _size + len : 2 * _capacity);
		}
		size_t end = _size + len;
		while (end >= pos + len) {
			_str[end] = _str[end - len];
			end--;
		}

		for (int i = 0; i < len; i++) {
			_str[pos + i] = str[i];
		}
		_size += len;
	}
	void string::erase(size_t pos, size_t len) {
		assert(pos < _size);

		if (len >= _size - pos) {
			_str[pos] = '\0';
			_size = pos;
		}
		else {
			for (int i = pos + len; i <= _size; i++) {
				_str[i - len] = _str[i];
			}
			_size -= len;
		}
	}


	size_t string::find(char ch, size_t pos) {
		for (int i = pos; i < _size; i++) {
			if (ch == _str[i]) {
				return i;
			}
		}
		return npos;
	}
	size_t string::find(const char* str, size_t pos) {
		assert(pos < _size);
		const char* ptr = strstr(_str + pos, str);
		if (ptr == nullptr) {
			return npos;
		}
		else {
			return ptr - _str;
		}
	}

	string string::substr(size_t pos, size_t len)
	{
		assert(pos < _size);

		// len大于剩余字符长度，更新一下len
		if (len > _size - pos)
		{
			len = _size - pos;
		}

		string sub;
		sub.reserve(len);
		for (size_t i = 0; i < len; i++)
		{
			sub += _str[pos + i];
		}
		
		return sub;
	}
	bool operator<(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) < 0;
	}
	bool operator<=(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) <= 0;
	}
	bool operator>(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) > 0;
	}
	bool operator>=(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) >= 0;
	}
	bool operator==(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) == 0;
	}
	bool operator!=(const string& s1, const string& s2) {
		return strcmp(s1.c_str(), s2.c_str()) != 0;
	}

	ostream& operator<<(ostream& out, const string& s) {
		for (auto ch : s)
		{
			out << ch;
		}

		return out;
	}
	istream& operator>>(istream& in, string& s) {
		s.clear();
		const int N = 256;
		char buff[N];
		int i = 0;
		
		char ch;
		ch = in.get();
		while (ch != ' ' && ch != '\n') {
			buff[i++] = ch;
			if (i == N - 1) {
				buff[i] = '\0';
				s += buff;
				i = 0;
			}
			ch = in.get();
		}
		if(i > 0){
			buff[i] = '\0';
			s += buff;
		}
		return in;
	}
	void string::clear() {
		_str[0] = '\0';
		_size = 0;
	}
}
